1. Field of the Invention
The present invention relates to the formation of curved crossflow screens and more particularly relates to a method and apparatus for simultaneously shaping initially circular looped wire to wedge-shaped looped wire and curving the sections of the wire extending between adjacent loops.
2. Prior Art
It is known to form looped and curved wedge wire elements for use in crossflow screens by means of an essentially three-step process. In the first step, after the wire has been successively looped along its length, the wire extending between successive loops is coined from an initially circular section to a wedge-shaped section. In the second step, the wedge-shaped sections are curved along the length thereof. In this second step, stresses are developed due to the relative stiffness of the wider side of the wedge-shaped sections, which cause the wedge-shaped sections to twist about their own axes. Accordingly, a third step is required wherein the curved wedge-shaped sections are twisted reversely about the axis of the wire so as to remove strains resulting from the stresses which caused the looped wire to twist about its own axis.
It has been known in the manufacture of carriage clips to simultaneously bend and cross sectionally re-form wire-like elements. Examples of techniques employed in the manufacture of carriage clips appear in U.S. Pat. Nos. 133,492 and 139,413.